47.3 IBUs as written...right in the middle of the BJCP guidelines for Am Stout...
More on the flavor/aroma adds?
If you were shooting to brew to style, and submit it to a competition, it would be beneficial to up the late/finishing hops - typically, with more American/citrus varieties. IBUs aren't really hops and hoppy beers aren't necessarily bitter beers.
But if you are brewing to taste, do what you want! I'm just letting you know that when you put 'American' in front of a stout it denotes the beer having a more than noticeable hop presence (at least if you want to score well).